Hi Wolfram,
On Thu, Jun 15, 2017 at 8:30 PM, Wolfram Sang
<wsa+renesas@xxxxxxxxxxxxxxxxxxxx> wrote:
> One helper checks if DMA is suitable and optionally creates a bounce
> buffer, if not. The other function returns the bounce buffer and makes
> sure the data is properly copied back to the message.
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -764,6 +767,68 @@ static inline u8 i2c_8bit_addr_from_msg(const struct i2c_msg *msg)
> return (msg->addr << 1) | (msg->flags & I2C_M_RD ? 1 : 0);
> }
>
> +/**
> + * i2c_check_msg_for_dma - check if a message is suitable for DMA
> + * @msg: the message to be checked
> + * @threshold: the amount of byte from which using DMA makes sense
> + * @ptr_for_bounce_buf: if not NULL, a bounce buffer will be attached to this
> + * ptr, if needed. The bounce buffer must be freed by the
> + * caller using i2c_release_bounce_buf().
> + *
> + * Return: -ERANGE if message is smaller than threshold
> + * -EFAULT if message buffer is not DMA capable and no bounce buffer
> + * was requested
> + * -ENOMEM if a bounce buffer could not be created
> + * 0 if message is suitable for DMA
> + *
> + * Note: This function should only be called from process context! It uses
> + * helper functions which work on the 'current' task.
> + */
> +static inline int i2c_check_msg_for_dma(struct i2c_msg *msg, unsigned int threshold,
> + u8 **ptr_for_bounce_buf)
__must_check?
Isn't this function a bit large to be inlined?
> +/**
> + * i2c_release_bounce_buf - copy data back from bounce buffer and release it
> + * @msg: the message to be copied back to
> + * @bounce_buf: the bounce buffer obtained from i2c_check_msg_for_dma().
> + * May be NULL.
> + */
> +static inline void i2c_release_bounce_buf(struct i2c_msg *msg, u8 *bounce_buf)
This one is smaller.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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